This invention relates generally to the containment of cryogenic fluids such as for storage or other purposes.
The storage or other containment of a cryogenic fluid involves the use of insulated vessels to reduce as much as possible the loss of some of the cryogenic fluid due to heat leak into the vessel. However, even with the use of the best insulation systems available, a significant portion of the contained cryogen will vaporize due to the heat leak, resulting in a pressure increase within the container to the point at which the vapor is vented to the atmosphere through safety valves. This loss of cryogenic fluid imposes a significant economic burden, especially for higher cost cryogenic fluids such as helium and neon which are used for such applications as superconductivity.
Accordingly it is an object of this invention to provide a system for storing or otherwise containing a cryogenic fluid which can reduce or eliminate losses due to heat leak into the fluid.
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
Method for providing refrigeration to a cryogenic vessel comprising:
(A) providing a pulse to a working gas to produce a compressed working gas, and cooling the compressed working gas to produce cooled working gas;
(B) expanding the cooled working gas in a cold end of a pulse tube to generate refrigeration to produce further cooled working gas; and
(C) providing refrigeration from the further cooled working gas to a cryogenic vessel which contains cryogenic fluid.
Another aspect of the invention is:
A cryogenic vessel system comprising:
(A) a vessel having an outer shell defining a vessel interior;
(B) a pulse generator, a regenerator, a cold heat exchanger, means for passing a pressure wave through working gas from the pulse generator to the regenerator, and means for passing a pressure wave through working gas from the regenerator to the cold heat exchanger; and
(C) a pulse tube having a cold end, said cold end being in flow communication with the cold heat exchanger, and said cold heat exchanger being at least in part within the vessel interior.
As used herein the term xe2x80x9ccryogenic fluidxe2x80x9d means a fluid which at atmospheric pressure is a gas at a temperature of 240 K.
As used herein the term xe2x80x9cregeneratorxe2x80x9d means a thermal device in the form of porous distributed mass, such as spheres, stacked screens, perforated metal sheets and the like, with good thermal capacity to cool incoming warm gas and warm returning cold gas via direct heat transfer with the porous distributed mass.
As used herein the term xe2x80x9cpulse tubexe2x80x9d means a refrigerator device to produce low temperature refrigeration using suitable components including a pulse generator.
As used herein the term xe2x80x9corificexe2x80x9d means a gas flow restricting device placed between the warm end of the pulse tube expander and a reservoir in a pulse tube refrigerator.
As used herein the term xe2x80x9cpressure wavexe2x80x9d means a mass of gas that goes through sequentially high and low pressure levels in a cyclic manner.